Why we should open the windows when there is a gas leak?

Why we should open the windows when there is a gas leak (洩漏)?
Ans: There are two reasons for opening the windows when there is a gas leak.
It is to let the circulating (流動的) air come in so as to avoid from being poisoned (中毒).
It is to let the wind blow away (吹散) the gas so as to reduce the intensity (強度) of it.